Various embodiments of the present invention relate in general, to illumination devices, and more particularly, to light emitting diode (LED) devices suitable for use in illumination applications, including uses as replacement bulbs in traffic lights and for home and industry lighting applications.
There are numerous applications that require light bulbs to be used in environments requiring frequent use, where changing a burned out light bulb can be cumbersome, expensive and/or otherwise inconvenient. For instance, a conventional traffic light provides three indicators, each indicator represented by a unique corresponding color. Typically, red is utilized as an instruction to stop, yellow is utilized as a warning of an impending stop instruction, and green is utilized as an instruction to go or otherwise travel.
A conventional traffic light houses three compartments, each compartment corresponding to a select one of the above-identified three colors. Within each compartment, an incandescent light bulb is typically utilized as the light source. Under this implementation, a reflector is mounted within the compartment behind the light bulb to reflect light from the incandescent light bulb out of the compartment through a color window or lens. However, the spectrum of light given off by an incandescent light bulb is broad and includes red, yellow and green light, as well as a fairly large percentage of infrared radiation. As such, to provide light at the appropriate color, a corresponding color cover lens is provided at the window in front of each light bulb to filter out the unwanted light so that only a single color, e.g., red, yellow or green light passes through. The remaining filtered energy is wasted as heat. As such, the efficiency of light emitted by a traffic light utilizing incandescent light sources is low. For example, the efficiency of a typical 100 W light bulb can be only about 2.6% or 17.5 lm/W (lumen per watt).
Additionally, in order to convert a typical traffic light to accommodate conventional light emitting diode (LED) bulbs, the whole fixture of the traffic light must be replaced, resulting in a conversion that is costly, labor intensive, and further requiring that traffic must be stopped during the installation.